Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
thu hang » thi hang, thuc hanh, thu huong
hieu van » hieu va, thien van, lieu va
truc va » thuc va, trung va
van cau » van dau, van hau, van chat
vu sach » vu bach, su sach, vu khach
mai hoi » mai khoi, dai hoi, lai hoi
cuu tre » cua tre, cau tren, cau treo
ma hoi » xa hoi, ma hoa, me hoi
vi cuu » vi luu, vinh cuu

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach thu hang ((ma hoi) OR (mai hoi)). hieu van cau ((truc va) OR (thuc vat)) hanh vi cuu tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach thu hang ((ma hoi) OR (mai hoi)). hieu van cau ((truc va) or (thuc vat)) hanh vi cuu tre~".
• Adding a wildcard symbol may retrieve word variants: vu sach thu hang ((ma hoi) OR (mai hoi)). hieu van cau ((truc va) or (thuc vat)) hanh vi cuu tre*.